10 BUTTER-M AKING 
carmine, and the cream washed with water until it is free 
from milk-sugar, a stained layer is present around each globule. 
(2) He has succeeded in isolating this gelatinous substance 
from cream and butter. Owing to its existence in these two 
substances, he assumes that it is also present in milk. 
(3) When ether is added to milk, the fat globules dissolve 
with difficulty, unless some alkali is added to the milk first. 
(4) Bichamp maintains that when ether is added to milk 
the fat-globules are enlarged due to the ether passing through 
the supposed membrane by the process of osmosis. He con- 
siders this fact sufficient to prove that there is a membrane 
encircling each globule. 
(5) Butter containing 85 to 86% fat is asserted by Rich- 
mond to have the same consistency as cream containing about 
72% fat at the same temperature. The solidity of butter 
is due to the close proximity of the fat-globules. Now, if 
cream with less fat has the same consistency as butter, the 
proximity of the fat-globules must be equal to that of the 
butter; this would indicate that there is a membrane and 
that this membrane increases the size of the fat-globules. 
(6) The fact that cream separated by centrifugal force is 
more easily churned than cream of same richness separated 
by gravity methods, would also be explained if the fat glob- 
ules in milk had such a membrane surrounding them. 
This membrane, or what is believed to be a membrane, 
Storch has isolated and analyzed. He finds it to consist of 
94% of water and 6% of proteid. 
The reasons deduced by Storch are strong; and the behavior 
of cream and butter renders it probable that there is such a 
membrane enveloping each globule of fat. 
CLasses OF Farts. 
There are two great classes or groups of fats present in the 
butter, namely: 
(1) Volatile and Soluble, 
(2) Non-volatile and Insoluble. 
